Air conditioning apparatus having control means



P. EDBERG Nov. 14, 1950 AIR CONDITIONING APPARATUS HAVING CONTROL MEANS Filed June 9, 1945 ATTORN EY I .,--,,......".,--.-"-..,....--rl 1 I I INVENTOR Patented Nov. 14, 1950 AIR CONDITIONING APPARATUS HAVING CONTROL MEANS Per Edberg, Evansville, Ind., assignor to Serve], Inc., New York, N. Y., a corporation of Delaware Application J line 9, 1945, Serial No. 598,537

9 Claims.

This invention relates to air-conditioning systems and particularly .to means for controlling the circulation of air over the evaporator or cooling element of such systems In air-conditioning systems it is common practice to provide an evaporator or cooling element in an air duct and to circulate air through the ductv and over the evaporator. With some systems the evaporator is supplied with a refrigerant or coolin liquid at the upper portion thereof, which cooling medium flows downward through the several sections or tubes of the evaporator. When such a system is operating on full input, all of' the tubes of the evaporator are supplied with liquid refrigerant and consequently, the entire evaporator acts as a cooling element. During such operation, as latent heat is removed from the airthat is being cooled, condensate collects on the several tubes, and in the case when horizontal tubes are .used, this condensate drips from the upper to the lower tubes. In the case when vertical tubes are used, this condensate trickles downward over the tubes. In either case, so long as suflicient liquid refrigerant is supplied to the several tubes of the evaporator that substantially the entire evaporator functions to cool the air which passes over the evaporator, the condensate that collects on the evaporator tubes merely drips or trickles from the upper to the lower portions thereof, which condensate is collected below the evaporator and disposed of in any suitable manner.

When such a system is operating on reduced input, half input for example, only the upper half of the evaporator functions to cool the air. In cases where the refrigerating medium is a liquid which evaporates as it passes through the evaporator, all of the liquid is evaporated or spent as it passes through the upper half of the evaporator. In cases where the refrigerating medium is intended to remain in a liquid state in passing through the cooling element, this liquid picks up suflicient heat in passing through the upper half of the cooling element that it does not function as a cooling medium in the lower half of the cooling element. In either case, the condensate that is removed from the air drips or trickles from the upper half of the evaporator or cooling element on to the lower. half thereof, which condensate is re-evaporated by the relatively warm air which passes over the lower half of the cooling element. This re-evaporation of the condensate is objectionable in that it is a direct loss in latent heat removal.

It is, therefore, desirable to block of! or prevent the flow of air ver that portion of the cooling element which is not furnished with refrigerant when the system is operated on reduced input. It is also desirable to simultaneously'by-pass a corresponding volume of air around the cooling element so that the total air resistance and air volumes are maintained consistent with proper blower operation.

I have invented an air-conditioning system wherein that portion of the cooling element which is not furnished with refrigerant when operated on reduced input is blocked oil and the. air that would normally pass ver this portion of the cooling element is by-passed around the cooling element. blocked off and the volume of air that is bypassed is automatically controlled by the temperature of several sections f the cooling element.

In the illustrated embodiment of this invention, the above and other objects and advantages are accomplished by providing a series of shutters or dampers in the duct through which the air to be conditioned is circulated. These shutters are so arranged and controlled that on reduced input as the lower sections of the cooling element become warm due to a lack of refrigerant in these sections, the shutters located in front of these sections are closed one after the other and as one f these shutters is closed, a by-pass shutter is opened. By this arrangement, the moisture which condenses on the upper or refrigerated sections of the cooling element and drips therefrom on to the lower or unrefrigerated sections of the cooling element, when the system is operated on reduced input, is not re-evaporated but finally drips from the lower sections into a drain trough or the like. As the load on the system increases, that is as the system approachesfull input operation, the lower sections of the cooling unit are furnished with refrigerant, causing the temperature of these sections to fall which, in turn, causes the shutters in front of these sections to open and the by-pass shutter to close, whereby all of the air being conditioned passes over the cooling element.

Referring now to the drawing, wherein a preferred embodiment of this invention is illustrated, and wherein:

.Fig, 1 is a diagrammatic view of an air-conditioning system incorporating this invention; and

Fig. 2 is a diagrammatic view illustrating the electric control circuit used in the system of Fig. 1.

Referring to Fig. 1, the invention is shown in connection with a heating and cooling system The area of the cooling element that is.

comprising a heating element or radiator III and a cooling element or evaporator I I arranged in a duct system. The duct system includes a duct I2 through which air is withdrawn from a room or other enclosure I3 by a blower I4, the air being discharged by the blower into a duct i5 through which it is returned to the enclosure. The duct I2 may contain a suitable filter, shown as a plurality of pads I5, and a humidifier II. The humidifier is provided with a water supply conduit I8 and a drain conduit I3. During operation of the heating unit or the cooling unit as the case may be, heating or cooling effect is transmitted either by heating element III or cooling element II to air flowing through the duct system.

The cooling element I I forms part of a refrigerating unit, and while this invention is not limited to a particular type of refrigerating unit it is preferred to use a two-pressure absorption type unit such as that illustrated and described in the United Statespatent to P. P. Anderson, Jr., No. 2,352,930, granted'July 4, 1944. For purposes of describing this invention, only the essential parts of this Anderson refrigerating unit are included in this application. However, this Anderson patent may be considered as incorporated in this application and reference may be had thereto for a detailed description of the refrigerating unit, the heating unit and the controls therefor.

Liquid refrigerant, such as water, is supplied to the evaporator or cooling element II by a condenser 20. Condenser is connected by a conduit 20 to the upper portion of the evaporator II.

Conduit 20' may be in the form of a U-tube as shown, for example, in the above patent to P. P. Anderson, Jr. The liquid reirigerant flows into and through the upper tubes of evaporator II, and from there the liquid refrigerant flows downward in series through the lowertubes. The liquid refrigerant evaporates in the evaporator tubes and produces the desired cooling effect upon the air flowing over the evaporator tubes. From the evaporator tubes, the vaporized refrigerant flows into headers (not shown) at each end of the evaporator and from the headers the refrigerant vapor flows into an absorber 2I where the vapor" is absorbed into an absorption solution. such as, for example, asolution of lithium chloride. When the system is operated on full input, liquid refrigerant issupplied to substantially all of the tubes of evaporator II and all of the air that passes over the evaporator tubes is cooled by the vaporization of this liquid refrigerant within the tubes. However, as stated above, when the system is operated on reduced input such as, for example, half load, the liquid refrigerant that is supplied to the evaporator is evaporated in passing through the upper half of the evaporator leaving the lower half of the evaporator without a supply of liquid refrigerant. This causes the tubes of the lower half of the evaporator to warm up with the result that condensed moisture which accumulates on the upper tubes and drips therefrom on to the lower tubes is reevaporated by the heat of the air passing over the lower tubes.

In accordance with this invention, a pair of shutters or dampers 22 and 22' are located immediately in front of the tubes which form the lower half of evaporator II. These shutters, which are pivotally supported in any suitable manner in the air duct, are operated by a pair of solenoids 23 and 23' having coils 24 and 24 and cores 25 and 25'. Cores 25 and 25' are operatively connected to the respective shutters by links 26 and 4 26' and cranks 21 and 21'. A third shutter 01 damper 30 is located in a by-pass channel formed in theair duct between absorber H and a drip pan or tray 3|. Drip tray 3| is formed with a horizontal lip 32 which assists in blocking the passage of air through the lower part of evaporator l I when shutter 22 is in closed position, as I shown in Fig. 1. Shutter 30 is pivotally mounted in the air duct in any suitable manner and is operated by a compound solenoid 33. Solenoid 33 is provided with two coil sections 33a and 33b and a core 35. Core 35 is operatively connected to shutter 30 by a link 36 and a crank 31. Soleholds 23 and 23' are energized and deenergized in accordance with the temperature of certain of the tubes of evaporator II. As shown in Fig. l, a sensing bulb 38 for controlling the energization of solenoid 23, is arranged in thermal relation with a tube Ila of evaporator II and a sensing bulb 3B, for controlling the energization of solenoid 23, is arranged in thermal relation-with a tube I Ib of the evaporator.

Referring to the control system and wiring dia gram of Fig. 2, sensing bulb 38 is connected to an expansible-contractible bellows 39 by a capillary tube 40, and sensing bulb 38' is connected to an expansible-eontractible bellows 39' by capillary tube 40'. 'Bellows 39 and 33' are supported in any suitable manner.and are provided with s pins M and M adapted to operate a pair of microswitches 42 and 42'. Power for operating the solenoids 23, 23' and 33 is supplied from a main 43 through a transformer 44, a secondary 45 of which is connected between the solenoids 23 and 23' by a line 46 and a return line 41. Contacts 420; and 42'a of switches 42 and 42' are connected respectively by lines 48 and 43 to coils 24 and 24' ofsolenoids 23 and 23'. Coil 24 is connected directly to return line 41 and coil 24' is connected to return line 41 by aline 50. Coil 33a of solenoid 33 is connected to line 48 by a, line 5| and to return line 41 by a line 52. Coil 33b of solenoid 33 is connected to line 49 by a line 53 and to return line 41 by a line 54. It will thus be evident that expansion of the bellows 33' in response to an increase in temperature of the evaporator tube I ID will close the switch 42' and energize the solenoid 23 which, in turn, closes the shutter .22 blocking the flow of air past the lower portion of evaporator I I. Simultaneous with the energization of solenoid 23', the coil section 3311 of compound solenoid 33 is energized, causing shutter 30 to open part way and by-pass the air that is blocked by the closing of shutter 22. Should the load on the unit be decreased further or to the extent that liquid refrigerant is no longer supplied to the tube Ha of evaporator II, bellows 33 expandsvclosing switch 42 and energizing solenoid 23 which, in turn, closes shutter 22. Simultaneous with the energization of solenoid 23, coil section 33a of s'fienoid 33 is energized, causing the shutter 30 to fully open the by-pass.

As the load on the system increases, that is, as the system approaches full input operation, liquid refrigerant will be supplied to the lower tubes of the evaporator. When liquid refrigerant reaches tube Ia of the evaporator, the temperature of this tube will drop causing bellows 39 to contract and open switch 42 deenergizing V ter 25 is opened and shutter 30 is closed fully. Shutters 22 and 22' are biased toward open position by suitable springs 23a and shutter 30 is biased toward closed position by a suitable spring 31a, whichsprings are shown only in Fig. 2.

The construction and operation of the heating element or radiator In, which is not a part of this invention, is fully illustrated and described in the aforementioned patent to P. P. Anderson, Jr., and need not be described here. However, it isto be noted that suitable means (not shown) are provided for rendering the shutters 22, 22'

and 30 inoperative during periods when the airconditioning system is operating on heating cycles. In other words, when the system is functioning to heat the space l3, shutters 22 and 22' remain open and shutter 30 remains fully closed. This may be accomplished by providing a suitable cut-out switch (not shown) in the line 46, for example. This switch may be operated manually or it may be operated automatically when the system is shifted from heating to cooling and from cooling to heating.

Although a single embodiment of the invention has been shown and described for purposes of illustration, the invention may take other forms and be variously applied within the scope of the following claims.

What is claimed is:

1. An air-conditioning system including an air duct, a cooling element located in said air duct, said cooling element including a plurality of sections arranged in vertical spaced relation one directly above another, a blower for conveying air through said air duct and over said cooling element, means operable responsive to the temperature of certain lower sections 01' said cooling element for blocking flow of air over said certain lower sections while continuing the flow of air over certain upper sections thereof, and means opoatively connected to said last named means for by-passing air around said cooling element.

2. An air-conditioning system comprising an air duct, an evaporator in said air duct, said evaporator including a plurality of horizontal tubes arranged in vertical spaced relation, means for supplying a cooling medium to the upper portion of said evaporator for gravity flow therethrough, means for conveying air through said air duct and over said evaporator tubes, and means in said air duct for blocking flow of air over the lower tubes of said evaporator and for simultaneously by-passing air around said lower tubes, said last-named means being controlled responsive to the temperature of certain of said lower tubes.

3. An air-conditioning system having an air cooling element of which a plurality of portions are so located one above another that cooling medium flows downward in series therethrough and moisture condensed from air flowing in contact with said portions drains downward in series thereon, means for supplying cooling medium to an upper of said portions of the cooling element, and means operativeto check flow of air in contact with a lower of said portions of the cooling element responsive to change in a condition affected by decrease in cooling of said lower portion.

4. An air-conditioning system comprising an air duct, a vertically-disposed cooling element in said air duct, means for conveying air through said duct and over said cooling element, means for supplying cooling medium to an upper portion Of said cooling element for series flow downward therethrough, whereby under certain conditions of operation the cooling effect of said cooling medium is spent in passing through the upper portion of said cooling element, means for blocking the flow, of air over the lower portion of said cooling element, said last-named means including a plurality of shutters located in front of the lower portion of said cooling element, and thermostatically-controlled means for operating said shutters in sequence.

5. An air-conditioning system including a chamber, a cooling element in said chamber,

means for supplying a cooling medium to said cooling element, means for conveying air over said cooling element, means for blocking the flow of air over selected portions of said cooling element in response to the temperature of said portions, said last-named means including a series of shutters with one shutter located in front of each of said selected portions, means for operating said shutters individually in sequence, and a damper for by-passing air around the selected portions of said evaporator, said damper being operatively connected to said series of shutters in such a manner that the damper is opened in proportion to the closing of said shutters.

6. An air-conditioning system comprising an air duct, an evaporator in said air duct, said evaporator including a plurality of verticallyaligned horizontal sections, means for supplying liquid refrigerant to the upper sections of said evaporator for downward flow therethrough, means for conveying air through said air duct and over said evaporator, a plurality of verticallyaligned shutters in said air duct immediately in front of the lower evaporator sections,-m'eans operable responsive to the temperature of said lower evaporator sections for operating said shutters in sequence, and a damper in said duct operatively connected to said shutters for by-passing air around said lower evaporator sections in accordance with the operation of said shutters, the construction andarrangement being such that under certain conditions of operation refrigerant supplied to the upper sections of the evaporator is spent in passing therethrough, whereby said shutters are closed, said damper is opened, air which would otherwise flow over the lower sections of said evaporator is bypassed around said evaporator and condensate which collects on the upper evaporator sections and drips therefrom on to the lower sections of said evaporator is out of the path of air flow through said duct.

7. In an air-conditioning'system of the type wherein air is cooled by contact with the exterior surface of a, cooling element formed of a plurality of vertically-aligned horizontal sections,, through the interior of which sections a cooling medium is circulated, that improvement which consists in flowing air over the plurality of cooling element sections during full load operations, blocking the flow of air over the lowermost sections of the cooling element during periods of operation on reduced input responsive to the temperature of'said lowermost sections while continuing to flow air over the upper sections, and by-passing air around the cooling element simultaneous with the blocking of the flow of air over said lowermost sections.

8. In an air-conditioning system of the type wherein air is cooled by contact with the exterior surface of a cooling element formed of a plurality of sections, through the interior of which 'element a cooling medium is circulated, that improvement which consists in flowing air over the plurality of cooling element sections during full load operation, blocking the flow of air over certain of the cooling element sections during periods of operation on reduced input responsive to the air is cooled by contact with the exterior surface of a cooling element formed of a plurality of portions arranged one directly above another, that improvement which consists-in flowing a cooling medium into the upper portions of said cooling element for series flow therethrough and into the lower portions of the cooling element during periods of full input operation while flowing air .0

over the entire cooling element, reducing the amount of cooling medium delivered to the upper portions of said cooling element during low load periods of operation, whereby the refrigerating effect of said cooling medium is spent in passing through the upper portions of said cooling ele ment, blocking the flow of air over the lower portions of said cooling element responsive to a rise in temperature of said lower portions while continuing to flow air over the upper portions of said cooling element, whereby condensate which collects on the upper portions of said cooiing element and flows therefrom onto the lower portions thereof during periods of low load operations flows from the lower portions of said cooling element in the form of liquid.

1 Pm EDBERG.

REFERENCES CITED UNITED STATES PATENTS Name, Date Palmer Aug. 31, 1937 Number 

